Logging in offline

Over two years ago, I described some of the advantages of U2F over OTP when FIDO keys were extremely new and not common at all. I have since moved most of my login access that support it to U2F, but the amount of services support it is still measly, which is sad. On the other hand, just a couple of days ago Facebook added support for it which is definitely good news for adoption.

But there is one more problem with the 2-factor authentication or, as some services now more correctly call it, 2-step verification: the current trend of service-specific authentication apps, not following any standard.

Right now my phone has a number of separate apps that are either dedicated as authentication app, or has authentication features built into a bigger app. There are pros and cons with this approach of course, but at this point I have at least four dedicated authorization apps (Google Authenticator, LastPass Authenticator, Battle.net Authenticator and Microsoft’) plus a few other apps that simply include authentication features in the same service client application.

Speaking of Microsoft’s authenticator app, which I didn’t like above. As of today what I had installed, and configured, was an app called “Microsoft Account” – when I went to look for a link I found out that it’s just not there anymore. It looks like Microsoft simply de-listed the application from the app store. Instead a new Microsoft Authenticator is now available, taking over the same functionality. It appears this app comes from their Azure development team, from the Play Store ID, but more important it is the fourth app that appears just as Authenticator on my phone.

Spreading the second factor authentication across different applications kind of make sense: since the TOTP/HOTP (from now I will only call them TOTP, I mean both) system relies on a shared key generated when you enroll the app, concentrating all the keys into a single application is clearly a bit of a risk – if you could easily access the data of a single authentication app and fetch all of its keys, you don’t want it to bring you access to all the services.

On the other hand, having to install one app for the service and one for the authentication is … cumbersome. Even more so when said authentication app is not using a standard procedure, case in point being the Twitter OTP implementation.

I’m on a plane, I have a “new” laptop (one I have not logged on Twitter with). I try to login, and Twitter nicely asks me for the SMS they sent to my Irish phone number. Ooops, I can’t connect phone service from high up in the air! But fear not it tells me that I can give them a code from the backups (on a different laptop, encoded with a GPG key I have with me but not at hand in the air) or a code from the Twitter app, even if I’m offline.

Except, you need first to have it set up. And that you can’t do offline. But turns out if you just visit the same page while online it does initialize and then work offline from them on. Guess when you may want to look for the offline code generator for the first time? Compare with the Facebook app, that also includes a code generator: once you enable the 2-step verification for Facebook, each time you log in to the app, a copy of the shared key is provided to the app, so every app will generate the same code. And you don’t need to request the code manually on the apps. The first time you need to login, with the phone offline, you’ll just have to follow the new flow.

Of course, both Facebook and Twitter allows you to add the code generator to any authenticator TOTP app. But Facebook effectively set that up for you transparently, on as many devices as you want, without needing a dedicated authentication app, just have any logged in Facebook app generate the code for you.

LastPass and Microsoft authenticator apps are dedicated, but both of them also work as a generic OTP app. Except they have a more user-friendly push-approval notification for their own account. This is a feature I really liked in Duo, and one that, with Microsoft in particular, makes it actually possible to log in even where otherwise the app would fail to log you in (like the Skype app for Android that kept crashing on me when I tried to put in a code). But the lack of standardization (at least as far as I could find) requires you have separate app for each of these.

Two of the remaining apps I have installed (almost) only for authentication are the Battle.net and Steam apps. It’s funny how the gaming communities and companies appears to have been those pushing the hardest at first, but I guess that’s not too difficult to imagine when you realize how much disposable money gamers tend to have, and how loud they can be when something’s not to their liking.

At least the Steam app tries to be something else beside an authenticator, although honestly I think it falls short: finding people with it is hard, and except for the chat (that I honestly very rarely use on desktop either) the remaining functions are so clunky that I only open the app to authenticate requests from the desktop.

Speaking of gaming community and authentication apps, Humble Bundle has added 2FA support some years ago. Unfortunately instead of implementing a standard TOTP they decided to use an alternative approach. You can choose between SMS and a service called Authy. The main difference between the Authy service and a TOTP app is that the service appears to keep a copy of your shared key. They also allow you to add other TOTP keys, and because of that I’m very unhappy with the idea of relying such a service: now all your key are not only concentrated on an app on your phone, but also on a remote server. And the whole point of using 2FA, for me, is that my passwords are stored in LastPass.

There is one more app in the list of mostly-authenticator apps: my Italian bank’s. I still have not written my follow up but let’s just say that my Italian bank used TOTP-token authentication before, and have since moved to an hybrid approach, one such authentication system is their mobile app, which I can use to authenticate my bank operations (as the TOTP-token expired over a year ago and have not replaced yet). It’s kind of okay, except I really find that bank app too bothersome to use and never bother using it right now.

The remaining authentication systems either send me SMS or are configured on Google Authenticator. In particular, for SMS, the most important services are configured to send me SMS to my real Irish phone number. The least important ones, such as Humble Bundle itself, and Kickstarter, which also insist on not even letting me read a single page without first logging in, send their authentication code to my Google Voice phone number, so they require an Internet connection, but that also means I can use them while on a flight.

Oh yes, and of course there are a couple of services for which the second factor can be an email address, in addition, or in place, of a mobile phone. This is actually handy for the same reason why I send them to Google Voice: the code is sent over the Internet, which means it can reach me when I’m out of mobile connectivity, but still online.

As for the OTP app, I’m still vastly using the Google Authenticator app, even though FreeOTP is available: the main reason is that the past couple of years finally made the app usable (no more blind key-overwrites when the username is the only information provided by the service, and the ability to change the sorting of the authenticator entries). But the killer feature in the app for me is the integration with Android Wear. Not having to figure out where I last used the phone to log in on Amazon, and just opening the app on the watch makes it much more user friendly – though it could be friendlier if Amazon supported U2F at this point.

I honestly wonder if a multiple-weeks battery device, whose only service would be to keep TOTP running, would be possible. I could theoretically use my old iPod Touch to just keep an Authenticator app on, but that’d be bothersome (lack of Android Wear) and probably just as unreliable (very shoddy battery). But a device that is usually disconnected from the network, only dedicated to keep TOTP running would definitely be an interesting security level.

What I can definitely suggest is making sure you get youserlf a FIDO U2F device, whether it is the Yubico, the cheaper, or the latest BLE-enabled release. The user friendliness over using SMS or app codes makes up for the small price to pay, and the added security is clearly worth it.

4 thoughts on “Logging in offline

  1. Steam is actually also TOTP under the hood, just with a nonstandard way of going from the raw crypto output to a generated code. You don’t have to use the Steam app.

    Like

  2. > I honestly wonder if a multiple-weeks battery device, whose only service would be to keep TOTP running, would be possible.Like RSA secureID tokens, and similar devices? Yeah. Maybe some arduino project could do it.

    Like

  3. Yup like that but configurable somehow. Like a single cheap (resistive) touch screen where you can scroll across multiple TOTPs like on the Android Wear watch.Wondering how many pieces would be needed (RTC, display, camera for the QR code?)

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s